Designing weld groups subjected to eccentric loads is a common challenge in steel construction, especially in connections like brackets, base plates, and lifting lugs. Unlike concentric loading, eccentric forces introduce additional torsion and bending moments that must be properly accounted for. This Eccentrically Loaded Weld Group Analysis Excel Sheet makes that process faster, safer, and more accurate.
The Challenge of Eccentric Weld Loading
When a load is applied at a distance from the centroid of a weld group, it creates a moment arm that induces a torsional component on the weld pattern. Every element of the weld group then carries a combination of direct shear (from the applied force) and torsional shear (from the eccentric moment). The most highly stressed weld element — the critical location — determines the required weld size.
This situation arises constantly in practice: bracket connections to columns, shelf plate supports, corbels with welded connections, and any attachment where load is applied off-centre from the weld centroid.
Analysis Methods Implemented
This sheet implements the elastic (vector) method as the primary analysis approach, resolving the weld group's polar moment of inertia and combining direct and torsional shear at each weld element to find the governing stress location. Where a more refined result is needed, the instantaneous center of rotation (ICR) method is also available, allowing a direct comparison between the conservative elastic solution and the less conservative ICR solution for the same weld group.
What This Excel Sheet Calculates
- Weld group centroid location and polar moment of inertia
- Direct shear stress from the applied force
- Torsional shear stress from the eccentric moment
- Resultant stress at each weld element and the governing location
- Required weld size for the governing stress
- Comparison between elastic and ICR method results
Design Inputs Required
- Weld group layout (segment lengths, spacing, and orientation)
- Applied load magnitude, direction, and eccentricity
- Weld size and electrode classification
- Base metal and connected material properties
- Connection type (bracket, base plate, lug, or corbel)
Applicable Design Codes
This sheet follows the AISC-ASD 9th Edition Manual of Steel Construction weld provisions, with results that can also be cross-checked against AISC 360 for comparison where noted.
Who Should Use This Tool
This tool is intended for engineers checking bracket, base plate, corbel, and lug weld connections subject to eccentric loading in industrial and structural applications.
Download the Free Eccentric Weld Group Analysis Sheet
This free Excel sheet analyzes eccentrically loaded weld groups using both the elastic vector method and the instantaneous center of rotation method, letting engineers compare results side by side. Rather than manually calculating the polar moment of inertia and iterating toward an ICR solution, users can input the weld layout and load eccentricity directly and get the governing weld stress and required weld size in seconds, which is useful for bracket, base plate, and corbel connections.
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